Recovery of nitrated kerosene



economical. trated kerosene also failed because of the over- PatentedMay 20, 1952 TUNITEDSTATES PATENT OFFICE RECOVERY OF NITRATED KEROSENERobert A. Shutter, Terre Haute, Ind., assignor to Commercial SolventsCorporation, Terre Haute, Ind, a corporation of Maryland No Drawing;Application January 26, 1950, Serial No. 140,747

, My invention relates to the nitration of hydrocarbons and moreparticularly to the recovery of nitrated kerosene from crude reactionmixtures thereof. 7

Various methods of recovering the kerosene actually nitrated from asolution of crude nitrated kerosene have been used in the past, however,each of these methods has been attended by some outstanding diflicultywhich has prevented the smooth, economical and efiicient recovery longsought. 'For example, attempts, have been made to steam distill thekerosene from crude mixtures of nitrated kerosene and kerosene but thevapor pressures of the constituents of Intro-kerosene and keroseneoverlap and thus very poor separation of the components is obtained.Furthermore, the amount of steam required is so exceptionally high as tomake the process very un- Vacuum rectification of'crude nilappingboiling points of kerosene and nitrokerosene. Various solvent extractionprocesses have failed due to difliculties such as poor extraction A anddensity reversal of the components which occurs in the case ofcontinuous countercurrent methanol extraction.

The object of the present invention isto provide a simple, efficient,and economical process for the. recovery of kerosene actually nitratedfrom the crude reaction solutionof said nitrated kerosene. j J

I have found that about 98% of the material actually nitrated can berecovered from crude nitration reaction mixtures of nitrokerosene andkerosene by extraction with nitromethane. The

extraction can be carried out batchwise or it can be carried out in acontinuous'process' involving 'countercurrent extraction in a columnsuch as a packed column, a column containing plates, a

column depending on height alone for its efli ciency, or a Scheibelcolumn which lattertype is a column containing a number of so-calledstages, each stage comprising a packed section and a section wherein thematerial is agitated by means of a small propeller. In the applicationof batch extraction, the crude mixture of nitrated kerosene and keroseneis mixed with nitromethane, the mixture agitated and the lower layercomprising the nitrated kerosene and nitromethane then separated. In thecase of the con tinuous countercurrent extraction, the crude mixture ofnitrated kerosene and kerosene is introduced at the bottom of the columnand the nitromethane at the top. The mixture of extracted nitratedmaterial-in nitromethane is'then taken 8 Claims. (Cl. 260644) off at thebottom of the column while the spent 1 ally nitrated which is equivalentto approximately 25% by volume of the crude kerosene introduced into thenitration reaction. That being true, my invention providesa means foremciently and economically concentrating crude nitrokerosene intoapproximately one-fourth of its original volume. The reduction in volumewhich I obtain naturally depends on the amount of nitrated materialpresent in the crude nitration reaction mixture. My process, however, isoperative in recovering kerosene actually nitrated regardless of theoriginal concentration of nitrated material in the crude nitrationreaction mixture.

7 Furthermore, my process can be used for the recovery of nitratedkerosene from a mixture of nitrokerosene with any other materialprovided nitromethane is inert to said other material and provided thesolubility of said other material in nitromethane-nitrokerosene mixturesis very small.

In carrying out my invention, I have found that by heating the crudenitrokerosene and the nitromethane to from 60 to 90 C. beforeextraction, I can forestall the tendencyof the two fluids to emulsify,and, in the case of continuous extraction, reduce the separating time ofthe fluids at the interface. For batch extraction of the nitratedkerosene, it is not absolutely necessary to preheat the crudenitrokerosene and the nitromethane because the agitation is lessvigorous than in the continuous extraction process. However, I prefer topreheat the materials even in batch extraction.

In practicing my invention, I use from 0.5 to 2.0 volumes ofnitromethane per volume of crude nitrated kerosene and I prefer to useone volume of nitromethane per volume of crude nitrated kerosene. I havefound that amounts near the lower limit are characterized by slightlylower yields if appliedto usual concentrations (about .225% by volume)of nitrated kerosene in the crude nitration-reaction mixture." Theuppetl'imit-bf 'be recovered since there is some "loss.

amounts of'nitromethane to be used is determined by the solubility ofkerosene in nitromethane. If amounts above the limit set out above areused, the amount of kerosene in the final nitrokerosene product will beundesirably high. However, if the nitrokerosene concentration in thecrude nitration mixture is unusually high (above 30%) then amounts ofnitromethane in excess of the amount indicated above can be usedsatisfactorily.

The process of my invention is preferably carried out by dividing theamount of nitromethane into approximately 5 equal par-ts by volume andthen extracting the entire amount 1 of crude nitrated kerosene once witheach aliquot of nitromethane, solvent extract mixtures. If thecontinuous counter-current extraction method is chosen, the above resultis obtained by employing a column containing the number of theoreticalplates required to effect substantially complete transfer of thenitrokerosene from the reaction mixture to the nitromethane. Atheoreticalplate. could be an actual plate iisaid actual plate had anemciency of 100%, apacked section equivalent to a .theoretical plate, aheight of column equivalent sene and nitromethane and the upper layer ismade upof the spent crude kerosene. The

layers are. separated and the spent crude mate-' rial can be distilledto recover small amounts of dissolved nitromethane. If the continuous'ex- .traction processis chosen, the mixture of hitrated kerosene andnitromethane is taken ofli the column already separated from vthe :spentcrude kerosene.

The nitromethane is then removed'from'the nitratedkerosene by strippingit at reducedpressure. This enables distillation toproceed with outraising the temperature'to the decomposition point of the nitratedkerosene components. By

using a falling film column the diameter of which becomes progressivelysmaller down through its length, spraying the mixture of nitromethaneand nitrokerosene on the inner wallsat the top of the column and byusinga pressure of-approximately 100 mm. mercurypa'bout 98% of J thenitromethane can be removed very quickly. The entire amount ofnitromethane removed will not Incarrying out the nitromethane removal;it is'desirable to use a column such that onlyone pass-of the mixturethrough the column is required "but where necessary I make from'abouttwo-to four passes of the mixture through the column to obtain maximumefiiciency. r

The following example is ofieredto illustrate one embodiment or myinvention-though-it is to be understood that I-am notto-be limited tothe procedure as shown. I

Example A 148-ml. portion of nitromethane was :divided subsequentlycompositing the to stand for approximately minutes. The mixture settledinto two layers and the bottom layer, comprising a mixture of nitratedkerosene and nitromethane, was separated. The top layer 5 comprising thecrude nitration reaction mixture of nitrated kerosene and kerosene wasthen extracted with each of. the four. other 29:6 ml. portions ofnitromethane 'inithe I manner stated above. After the crude nitrationreaction mixture .1 of nitrated kerosene and kerosene had been extractedwith each of the aliquot portions of nitromethane, the product extractswere composited and the entire composited mixture of nitrated keroseneand nitromethane run two 15 times through a falling film column at apressure of 100 mm. mercury. From the column, 46 ml. .or nitratedkerosene corresponding to a .yield of "97% was obtained. Thenitromethane recovered amounted to 140 ml. or 95% of the amount used.

What I claim is:

1. A process for the recovery of the nitroparaflin components from amixture produced by the nitration of kerosene which comprisesextractingsaid crude mixture with nitromethane,

separating the layers which form, removing the nitromethane from theproduct .extract'by .a distillation adapted to minimize decomposition ofl the nitroparafiins, and thereby recovering .the

.nitrated kerosene.

2. A process for the. recovery.ofnitrokerosene which comprisesextracting said. nitrckerosene from crude nitration reaction:mixtureathereof with nitromethane; separating the extract layer whichforms, stripping the nitromethaneirom said extract layer,.and therebyrecovering .ithe .nitrated kerosene.

3. .A process for the recoveryof nitrokerosene which comprisesextracting said. nitrokerosene from crude nitration reactionmixturesl'thereof 40.with from 0.5 to 2.0'volumes-of. nitromethane,separating the extract layer -.which .forms, strippingthe nitromethanefromsaid extract layer, and thereby. recovering the .nitratedlkero-.sene.

.4. Aprocessi for the recovery. or. nitrokerosene from crude nitrationreaction -mixturesthereof which comprises extracting said..nitrokerosene with from 0.5 to 2.0 volumes of nitromethane at.atemperature sufficient to prevent.emulsifying 50Lbut insufficient tocause .decompositionpf the nitrokerosene, separating the layerswhich..form,

stripping the nitromethane from the .product layerat 0.1 to0.5-atmosphere -pressure/anti .there- -by. recovering the nitrated.kerosene.

5. A.process-for the recovery ofnitrokerosene .from crude-nitrationreaction mixtures "thereof which comprises -extracting saidnitrokerosene with.an equal volume. of nitromethaneata vtemperature of75 C., separating-thelayers which form, stripping the nitromethane fromthe-prod- .uct layer at-a pressure of 100 mmnmercuryand therebyrecovering the nitrated kerosene.

-6. In a process for the recoveryofnitrokerosene from crude nitrationreaction. mixtures thereof, the step which comprises extracting-saidnitrokerosene with nitromethane.

7. In a process for therecoveryaof nitrokerosene from crude nitrationreaction.-.mixtures thereof, the step which comprises extractingsaidnitrokerosene'with from 0.5 to 2.0 volumes of nitromethane at atemperature of-from 60 C.

to90 C.

: 8. .In .a process for therecovery.xof-thenitrdarafiin':componentsfrom.amixtureproducedby 15;;thenitrationgofrkerosene. -:the:- step ;.which :com-

prises extracting the said mixture with an equal UNITED STATES PATENTSvolume of nitromethane, said nitromethane and Number Name Date saidnitration mixture having been preheated to 2,511 433 Fiala June 13 1950a temperature suflicient to prevent emulsifying and insufficient tocause decomposition of said 5 OTHER REFERENCES nitropflrafiincompOnentS- Haas et al.: Chem. Reviews, vol. 32, pages 386- ROBERT A.SHURTER. 337 1943 REFERENCES CITED The following references are ofrecord in the 10 file of this patent:

1. A PROCESS FOR THE RECOVERY OF THE NITROPARAFFIN COMPONENTS FROM AMIXTURE PRODUCED BY THE NITRATION OF KEROSENE WHICH COMPRISES EXTRACTINGSAID CRUDE MIXTURE WITH NITROMETHANE, SEPARATING THE LAYERS WHICH FORM,REMOVING THE NITROMETHANE FROM THE PRODUCT EXTRACT BY A DISTILLATIONADAPTED TO MINIMIZE DECOMPOSITION OF THE NITROPARAFFINS, AND THEREBYRECOVERING THE NITRATED KEROSENE.